Node Manager Concept, Important Files

Server instances in a WebLogic Server production environment are often distributed across multiple domains, machines, and geographic locations. Node Manager is a WebLogic Server utility that enables you to start, shut down, and restart Administration Server and Managed Server instances from a remote location. 

A Node Manager process is not associated with a specific WebLogic domain but with a machine. 

You can use the same Node Manager process to control server instances in any WebLogic Server domain, as long as the server instances reside on the same machine as the Node Manager process. 

Node Manager must run on each computer that hosts WebLogic Server instances whether Administration Server or Managed Server that you want to control with Node Manager.

WebLogic Server provides two versions of Node Manager, Java-based and script-based, with similar functionality. However, each version has different configuration and security considerations.

Java-based Node Manager

• Java-based Node Manager runs within a Java Virtual Machine (JVM) process. 
• This version of Node Manager determines its configuration from the nodemanager.properties file.
• Java-based Node Manager provides more security than the script-based version.

Script-based Node Manager

• For UNIX and Linux systems, WebLogic Server provides a script-based version of Node Manager. 
• This script is based on UNIX shell scripts, but uses SSH for increased security. SSH uses user-id based security
• This version does not provide as much security as the Java-based version. 
• The advantage of the script-based Node Manager is that it can remotely manage servers over a network that has been configured to use SSH. No additional server installation is required. The scripts merely have to be copied to the remote machine.

What You Can Do with Node Manager

• Start, Shut Down, and Restart an Administration Server
• Start, Shut Down, Suspend, and Restart Managed Servers
• Monitor Servers and View Log Data

Starting Java-based Node Manager

Start scripts for Node Manager are installed in the WL_HOME\server\bin directory, where WL_HOME is the top-level installation directory for WebLogic Server. 

Use startNodeManager.cmd on Windows systems and startNodeManager.sh on UNIX systems.

The scripts set the required environment variables and start Node Manager in WL_HOME/common/nodemanager. Node Manager uses this directory as a working directory for output and log files. 

Important Node Manager Configuration Files

nodemanager.properties

This is the configuration file used by the Java-based version of Node Manager.

This file is located in WL_HOME/common/nodemanager.

nodemanager.hosts

This file contains a list of all the trusted hosts that can issue commands to Node Manager.

This file is located in WL_HOME/common/nodemanager.

nodemanager.domains

This file contains mappings between the names of domains managed by Node Manager and their corresponding directories. 

This file is located in WL_HOME/common/nodemanager.

nm_data.properties

This file stores the encryption data the Node Manager uses a symmetric encryption key. The data is stored in encrypted form.

This file is located in WL_HOME/common/nodemanager.

nm_password.properties

This file stores a username/password pair specific to the Node Manager server that is managing this domain. This is known as the Node Manager secret. The username and password are appended to a salt value (obtained from the SerializedSystemIni.dat of the domain) and SHA-hashed.

This file is located in DOMAIN_HOME/config/nodemanager.

boot.properties

Node Manager uses this file to specify a boot identity when starting a server. This file is located in domain-name/servers/server_name/data/nodemanager.

startup.properties

Each Managed Server instance has its own startup.properties file with properties that control how Node Manager starts up and controls the server. Node Manager automatically creates this file by using properties passed to Node Manager when the Administrative Server was last used to start the server. This allows a Node Manager client or startup scripts to restart a Managed Server using the same properties last used by the Administrative Server.

These properties correspond to the server startup attributes contained in ServerStartMBean and the health monitoring attributes in ServerStartMBean.

This file is located in domain-name/servers/server_name/data/nodemanager.

server_name.addr

server_name.addr stores the IP address added when a server starts or is migrated. This file is generated after the server IP address is successfully brought online during migration. server_name.addr is deleted when the IP address is brought offline. The server IP address is used to validate remove requests to prevent addresses being erroneously removed while shutting down the server.

This file is located in domain-name/servers/server_name/data/nodemanager.

server_name.lck

server_name.lck is generated by each server and contains an internally used lock ID.

This file is located in domain-name/servers/server_name/data/nodemanager

server_name.pid

server_name.pid is generated by each server and contains the process ID of the server. Node Manager checks the process ID generated by the server during crash recovery.

This file is located in domain-name/servers/server_name/data/nodemanager

server_name.state

server_name.state is generated by the server and contains the server's current state. Node Manager monitors the contents of this file to determine the current state of the server.

Note: Do not delete or alter this file. Without this file Node Manager cannot determine the current state of the server.

This file is located in domain-name/servers/server_name/data/nodemanager.